CVE-2021-42389Public exploitNetwork attack vector

Authenticated server crash via unchecked Delta modulus

Published Mar 14, 2022 · Updated Aug 4, 2024

Divide by zero in ClickHouse before 21.10.2.15-stable allows remote authenticated users to crash the server via a malicious query. The Delta decompressor treats the compressed buffer's first byte as a modulus divisor without rejecting zero, causing an arithmetic fault. Any account with read permission can reach the codec, and successful exploitation terminates the server process and interrupts database service.

CVSS severity6.5
Medium
EPSS probability1.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Divide by zero in ClickHouse before 21.10.2.15-stable allows remote authenticated users to crash the server via a malicious query. The Delta decompressor treats the compressed buffer's first byte as a modulus divisor without rejecting zero, causing an arithmetic fault. Any account with read permission can reach the codec, and successful exploitation terminates the server process and interrupts database service.

The record

CVE
CVE-2021-42389
Published
Mar 14, 2022
Updated
Aug 4, 2024
Vendor
ClickHouse
Product
ClickHouse
Classifications
CWE-369, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 14, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <21.10.2.15-stable

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

ClickHouse · ClickHouseversion=unspecified <21.10.2.15-stable

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.0NIST NVDAV:N/AC:L/Au:S/C:N/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-369Divide By Zero
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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